Electronic Device with Couplers for Power Wave Detection in Multiple Reference Planes

ABSTRACT

An electronic device may include signal transmission circuitry having a signal path and a signal source that transmits a signal on the signal path. First and second signal couplers may be coupled to the signal path. Control circuitry may use the first signal coupler to measure the signal at a first reference plane and may use the second signal coupler to concurrently measure the signal at a second reference plane. The signal measurements may include power wave, forward wave, reverse wave, impedance, and/or delivered power measurements. Terminations in the signal couplers may be adjusted to dynamically shift the reference planes. The first and second signal couplers may be formed from first and third metallization layers on a stacked dielectric substrate, where the signal path is formed from a second metallization layer. Additional signal couplers may be coupled to the signal path for concurrently measuring additional reference planes.

FIELD

This disclosure relates generally to electronic devices and, moreparticularly, to electronic devices with circuitry for transmittingsignals.

BACKGROUND

Electronic devices can be provided with signal transmission capabilitiesin which a signal is transmitted onto an output load via a signal path.Electronic devices with signal transmission capabilities includewireless electronic devices having a wireless transmitter that transmitsradio-frequency signals onto an output load such as an antenna. It canbe desirable to be able to measure one or more characteristics of thesignal path using the transmitted signal.

SUMMARY

An electronic device may include signal transmission circuitry having asignal source, a signal path, an output node coupled, and an outputload. For example, the signal transmission circuitry may be part ofwireless circuitry in the electronic device, the signal source may be apower amplifier, and the output load may be an antenna. The signalsource may transmit a signal to the output load over the signal path.

A multi-coupler may be disposed along the signal path. The multi-couplermay include at least a first signal coupler and a second signal coupler.Each signal coupler may be used to measure the signal within arespective reference plane along the signal path. The first signalcoupler may have one or more terminations with first impedances. Thefirst impedances may configure the first signal coupler to exhibit afirst reference plane along the signal path. The second signal couplermay have one or more terminations with second impedances that aredifferent from the first impedances. The second impedances may configurethe second coupler to exhibit a second reference plane along the signalpath that is different from the first reference plane. The first andsecond signal couplers may include power detectors or may includeswitching circuitry for measuring forward and reverse waves.

One or more processors may use the first signal coupler to measure thesignal at the first reference plane along the signal path. The one ormore processors may use the second signal coupler to measure the signalat the second reference plane along the signal path concurrent withmeasurement of the signal at the first reference plane using the firstsignal coupler. The signal measurements may include power wavemeasurements, forward wave measurements, reverse wave measurements,impedance measurements, and/or delivered power measurements, asexamples. The impedances of the termination(s) in the signal couplersmay be adjusted to dynamically shift the location of the correspondingreference planes on the signal path over time. To maximize isolation ofthe first and second signal couplers, the first and second signalcouplers and the signal path may be distributed between metallizationlayers on a stacked dielectric substrate. The multi-coupler may includemore than two signal couplers for concurrently measuring additionalreference planes along the signal path.

An aspect of the invention provides an electronic device. The electronicdevice may include a signal source. The electronic device may include anoutput load coupled to the signal source over a signal path, the signalsource being configured to transmit a signal to the output load over thesignal path. The electronic device may include a first signal couplercoupled to the signal path and having a first termination with a firstimpedance. The electronic device may include a second signal couplercoupled to the signal path and having a second termination with a secondimpedance different from the first impedance.

An aspect of the disclosure provides a method of operating an electronicdevice. The method can include with a signal source, transmitting asignal along a signal path. The method can include with a first signalcoupler coupled to the signal path, measuring a power wave of the signalat a first reference plane along the signal path. The method can includewith a second signal coupler coupled to the signal path, measuring apower wave of the signal at a second reference plane along the signalpath concurrent with measurement of the power wave at the firstreference plane by the first signal coupler, the second reference planebeing different from the first reference plane.

An aspect of the disclosure provides an electronic device. Theelectronic device can include an antenna. The electronic device aninclude a power amplifier coupled to the antenna over a signal path andconfigured to transmit a radio-frequency signal on the signal path. Theelectronic device an include a first signal coupler coupled to thesignal path. The electronic device an include a second signal couplercoupled to the signal path. The electronic device an include one or moreprocessors. The one or more processors can be configured to measure theradio-frequency signal at a first reference plane along the signal pathusing the first signal coupler. The one or more processors can beconfigured to measure the radio-frequency signal at a second referenceplane along the signal path using the second signal coupler concurrentwith measurement of the radio-frequency signal at the first referenceplane using the first signal coupler, the second reference plane beingdifferent from the first reference plane.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of an illustrative electronicdevice in accordance with some embodiments.

FIG. 2 is a diagram of illustrative signal transmission circuitry havingmulti-coupler circuitry for concurrently measuring multiple referenceplanes along a signal path in accordance with some embodiments.

FIG. 3 is a circuit diagram of illustrative multi-coupler circuitry thatcan measure both forward and reverse waves at first and second referenceplanes along a signal path in accordance with some embodiments.

FIG. 4 is a circuit diagram of illustrative multi-coupler circuitry thatcan measure both forward and reverse waves at a first reference planeand that can measure a power wave at a second reference plane along asignal path in accordance with some embodiments.

FIG. 5 is a circuit diagram of illustrative multi-coupler circuitry thatcan concurrently measure a power wave at first and second referenceplanes along a signal path in accordance with some embodiments.

FIG. 6 is a cross-sectional side view showing how an illustrativemulti-coupler may be distributed across multiple metallization layers ona substrate to maximize isolation between signal couplers within themulti-coupler in accordance with some embodiments.

FIG. 7 is a flow chart of illustrative operations that may be performedby an electronic device to concurrently characterize multiple referenceplanes along a signal path using multi-coupler circuitry in accordancewith some embodiments.

DETAILED DESCRIPTION

An electronic device such as device 10 of FIG. 1 may be a computingdevice such as a laptop computer, a desktop computer, a computer monitorcontaining an embedded computer, a tablet computer, a cellulartelephone, a media player, or other handheld or portable electronicdevice, a smaller device such as a wristwatch device, a pendant device,a headphone or earpiece device, a device embedded in eyeglasses or otherequipment worn on a user's head, or other wearable or miniature device,a television, a computer display that does not contain an embeddedcomputer, a gaming device, a navigation device, an embedded system suchas a system in which electronic equipment with a display is mounted in akiosk or automobile, a wireless internet-connected voice-controlledspeaker, a home entertainment device, a remote control device, a gamingcontroller, a peripheral user input device, a wireless base station oraccess point, a networking device, equipment that implements thefunctionality of two or more of these devices, or other electronicequipment. User equipment device 10 may sometimes be referred to hereinas electronic device 10 or simply as device 10.

As shown in the functional block diagram of FIG. 1 , device 10 mayinclude components located on or within an electronic device housingsuch as housing 12. Housing 12, which may sometimes be referred to as acase, may be formed of plastic, glass, ceramics, fiber composites, metal(e.g., stainless steel, aluminum, metal alloys, etc.), other suitablematerials, or a combination of these materials. In some situations,parts or all of housing 12 may be formed from dielectric or otherlow-conductivity material (e.g., glass, ceramic, plastic, sapphire,etc.). In other situations, housing 12 or at least some of thestructures that make up housing 12 may be formed from metal elements.

Device 10 may include control circuitry 14. Control circuitry 14 mayinclude storage such as storage circuitry 16. Storage circuitry 16 mayinclude hard disk drive storage, nonvolatile memory (e.g., flash memoryor other electrically-programmable-read-only memory configured to form asolid-state drive), volatile memory (e.g., static or dynamicrandom-access-memory), etc. Storage circuitry 16 may include storagethat is integrated within device 10 and/or removable storage media.

Control circuitry 14 may include processing circuitry such as processingcircuitry 18. Processing circuitry 18 may be used to control theoperation of device 10. Processing circuitry 18 may include on one ormore processors, microprocessors, microcontrollers, digital signalprocessors, host processors, baseband processor integrated circuits,application specific integrated circuits, central processing units(CPUs), graphics processing units (GPUs), etc. Control circuitry 14 maybe configured to perform operations in device 10 using hardware (e.g.,dedicated hardware or circuitry), firmware, and/or software. Softwarecode for performing operations in device 10 may be stored on storagecircuitry 16 (e.g., storage circuitry 16 may include non-transitory(tangible) computer readable storage media that stores the softwarecode). The software code may sometimes be referred to as programinstructions, software, data, instructions, or code. Software codestored on storage circuitry 16 may be executed by processing circuitry18.

Control circuitry 14 may be used to run software on device 10 such assatellite navigation applications, internet browsing applications,voice-over-internet-protocol (VOIP) telephone call applications, emailapplications, media playback applications, operating system functions,etc. To support interactions with external equipment, control circuitry14 may be used in implementing communications protocols. Communicationsprotocols that may be implemented using control circuitry 14 includeinternet protocols, wireless local area network (WLAN) protocols (e.g.,IEEE 802.11 protocols —sometimes referred to as Wi-Fi®), protocols forother short-range wireless communications links such as the Bluetooth®protocol or other wireless personal area network (WPAN) protocols, IEEE802.11ad protocols (e.g., ultra-wideband protocols), cellular telephoneprotocols (e.g., 3G protocols, 4G (LTE) protocols, 3GPP Fifth Generation(5G) New Radio (NR) protocols, etc.), antenna diversity protocols,satellite navigation system protocols (e.g., global positioning system(GPS) protocols, global navigation satellite system (GLONASS) protocols,etc.), antenna-based spatial ranging protocols, or any other desiredcommunications protocols. Each communications protocol may be associatedwith a corresponding radio access technology (RAT) that specifies thephysical connection methodology used in implementing the protocol.

Device 10 may include input-output circuitry 20. Input-output circuitry20 may include input-output devices 22. Input-output devices 22 may beused to allow data to be supplied to device 10 and to allow data to beprovided from device 10 to external devices. Input-output devices 22 mayinclude user interface devices, data port devices, and otherinput-output components. For example, input-output devices 22 mayinclude touch sensors, displays (e.g., touch-sensitive and/orforce-sensitive displays), light-emitting components such as displayswithout touch sensor capabilities, buttons (mechanical, capacitive,optical, etc.), scrolling wheels, touch pads, key pads, keyboards,microphones, cameras, buttons, speakers, status indicators, audio jacksand other audio port components, digital data port devices, motionsensors (accelerometers, gyroscopes, and/or compasses that detectmotion), capacitance sensors, proximity sensors, magnetic sensors, forcesensors (e.g., force sensors coupled to a display to detect pressureapplied to the display), temperature sensors, etc. In someconfigurations, keyboards, headphones, displays, pointing devices suchas trackpads, mice, and joysticks, and other input-output devices may becoupled to device 10 using wired or wireless connections (e.g., some ofinput-output devices 22 may be peripherals that are coupled to a mainprocessing unit or other portion of device 10 via a wired or wirelesslink).

Input-output circuitry 20 may include wireless circuitry 24 to supportwireless communications. Wireless circuitry 24 (sometimes referred toherein as wireless communications circuitry 24) may include two or moreantennas 30. Antennas 30 may be formed using any desired antennastructures for conveying radio-frequency signals. For example, antennas30 may include antennas with resonating elements that are formed fromloop antenna structures, patch antenna structures, inverted-F antennastructures, slot antenna structures, planar inverted-F antennastructures, helical antenna structures, monopole antennas, dipoles,hybrids of these designs, etc. Filter circuitry, switching circuitry,impedance matching circuitry, and/or other antenna tuning components maybe adjusted to adjust the frequency response and wireless performance ofantennas 30 over time. If desired, two or more of antennas 30 may beintegrated into a phased antenna array (sometimes referred to herein asa phased array antenna) in which each of the antennas conveysradio-frequency signals with a respective phase and magnitude that isadjusted over time so the radio-frequency signals constructively anddestructively interfere to produce a signal beam in a given pointingdirection.

The term “convey radio-frequency signals” as used herein means thetransmission and/or reception of the radio-frequency signals (e.g., forperforming unidirectional and/or bidirectional wireless communicationswith external wireless communications equipment). Antennas 30 maytransmit the radio-frequency signals by radiating the radio-frequencysignals into free space (or to free space through intervening devicestructures such as a dielectric cover layer). Antennas 30 mayadditionally or alternatively receive the radio-frequency signals fromfree space (e.g., through intervening devices structures such as adielectric cover layer). The transmission and reception ofradio-frequency signals by antennas 30 each involve the excitation orresonance of antenna currents on an antenna resonating element in theantenna by the radio-frequency signals within the frequency band(s) ofoperation of the antenna.

Wireless circuitry 24 may include one or more radios 26. Radio 26 mayinclude circuitry that operates on signals at baseband frequencies(e.g., baseband circuitry) and radio-frequency transceiver circuitrysuch as one or more radio-frequency transmitters 28 and one or moreradio-frequency receivers 34. Transmitter 28 may include signalgenerator circuitry, modulation circuitry, mixer circuitry forupconverting signals from baseband frequencies to intermediatefrequencies and/or radio frequencies, amplifier circuitry such as one ormore power amplifiers, digital-to-analog converter (DAC) circuitry,control paths, power supply paths, switching circuitry, filtercircuitry, and/or any other circuitry for transmitting radio-frequencysignals using antennas 30. Receiver 34 may include demodulationcircuitry, mixer circuitry for downconverting signals from intermediatefrequencies and/or radio frequencies to baseband frequencies, amplifiercircuitry (e.g., one or more low-noise amplifiers (LNAs)),analog-to-digital converter (ADC) circuitry, control paths, power supplypaths, signal paths, switching circuitry, filter circuitry, and/or anyother circuitry for receiving radio-frequency signals using antennas 30.The components of radio 26 may be mounted onto a single substrate orintegrated into a single integrated circuit, chip, package, orsystem-on-chip (SOC) or may be distributed between multiple substrates,integrated circuits, chips, packages, or SOCs.

Each radio 26 may be coupled to one or more antennas 30 over one or moreradio-frequency transmission lines 32. Radio-frequency transmissionlines 32 may include coaxial cables, microstrip transmission lines,stripline transmission lines, edge-coupled microstrip transmissionlines, edge-coupled stripline transmission lines, transmission linesformed from combinations of transmission lines of these types, etc.Radio-frequency transmission lines 32 may be integrated into rigidand/or flexible printed circuit boards if desired. One or moreradio-frequency lines 32 may be shared between multiple radios 26 ifdesired. Radio-frequency front end (RFFE) modules may be interposed onone or more radio-frequency transmission lines 32. The radio-frequencyfront end modules may include substrates, integrated circuits, chips, orpackages that are separate from radios 26 and may include filtercircuitry, switching circuitry, amplifier circuitry, impedance matchingcircuitry, radio-frequency coupler circuitry, and/or any other desiredradio-frequency circuitry for operating on the radio-frequency signalsconveyed over radio-frequency transmission lines 32.

Radio 26 may transmit and/or receive radio-frequency signals withincorresponding frequency bands at radio frequencies (sometimes referredto herein as communications bands or simply as “bands”). The frequencybands handled by radio 26 may include wireless local area network (WLAN)frequency bands (e.g., Wi-Fi® (IEEE 802.11) or other WLAN communicationsbands) such as a 2.4 GHz WLAN band (e.g., from 2400 to 2480 MHz), a 5GHz WLAN band (e.g., from 5180 to 5825 MHz), a Wi-Fi® 6E band (e.g.,from 5925-7125 MHz), and/or other Wi-Fi® bands (e.g., from 1875-5160MHz), wireless personal area network (WPAN) frequency bands such as the2.4 GHz Bluetooth® band or other WPAN communications bands, cellulartelephone frequency bands (e.g., bands from about 600 MHz to about 5GHz, 3G bands, 4G LTE bands, 5G New Radio Frequency Range 1 (FR1) bandsbelow 10 GHz, 5G New Radio Frequency Range 2 (FR2) bands between 20 and60 GHz, etc.), other centimeter or millimeter wave frequency bandsbetween 10-300 GHz, near-field communications frequency bands (e.g., at13.56 MHz), satellite navigation frequency bands (e.g., a GPS band from1565 to 1610 MHz, a Global Navigation Satellite System (GLONASS) band, aBeiDou Navigation Satellite System (BDS) band, etc.), ultra-wideband(UWB) frequency bands that operate under the IEEE 802.15.4 protocoland/or other ultra-wideband communications protocols, communicationsbands under the family of 3GPP wireless communications standards,communications bands under the IEEE 802.XX family of standards, and/orany other desired frequency bands of interest.

While control circuitry 14 is shown separately from wireless circuitry24 in the example of FIG. 1 for the sake of clarity, wireless circuitry24 may include processing circuitry (e.g., one or more processors) thatforms a part of processing circuitry 18 and/or storage circuitry thatforms a part of storage circuitry 16 of control circuitry 14 (e.g.,portions of control circuitry 14 may be implemented on wirelesscircuitry 24). As an example, control circuitry 14 may include basebandcircuitry (e.g., one or more baseband processors), digital controlcircuitry, analog control circuitry, and/or other control circuitry thatforms part of radio 26. The baseband circuitry may, for example, accessa communication protocol stack on control circuitry 14 (e.g., storagecircuitry 16) to: perform user plane functions at a PHY layer, MAClayer, RLC layer, PDCP layer, SDAP layer, and/or PDU layer, and/or toperform control plane functions at the PHY layer, MAC layer, RLC layer,PDCP layer, RRC, layer, and/or non-access stratum layer. If desired, thePHY layer operations may additionally or alternatively be performed byradio-frequency (RF) interface circuitry in wireless circuitry 24.

Electronic devices such as device 10 may include circuitry thattransmits signals. This circuitry includes a signal source, which can bemodeled as an arbitrary source impedance having a source power, that iscoupled to an output node over a signal path. The output node may becoupled to an output load having an output impedance. In signaltransmission systems such as these, it may be desirable to be able toperform measurements of the transmit signals at the output node. Forexample, measurements of power of the transmitted signals at the outputnode can be used to characterize the performance of the output load,which can then be used to calibrate subsequent signal transmissions, toadjust circuitry in device 10, or to perform other actions.

When the performance of the output load is characterized, measurementsare performed at a single reference plane along the signal path (i.e.,at the output node). Rather than only characterizing the performance ofa single reference plane, it may be desirable to be able to characterizethe performance of two or more locations along the signal pathconcurrently (e.g., simultaneously). This may, for example, allow thedevice to obtain robust real-time knowledge of the performance of thesignal path itself, which can then be used to modify device operationsto ensure that the signal path operates as expected over the lifespan ofdevice 10. The performance of the signal path may be characterized bymeasuring forward and/or reverse waves along the signal path, impedances(e.g., ratios of forward and reverse waves), and/or delivered powers(e.g., expressions involving forward waves and impedances) concurrentlyat multiple reference planes along the signal path.

In some implementations, a single signal coupler is disposed along thesignal path for performing measurements at a single reference planealong the signal path. Depending on the measured quantities and thedesired reference planes, different terminations and devices may beneeded to perform measurements of multiple different reference planes.As such, a single signal coupler is unable to perform concurrentmeasurements at multiple reference planes along the signal path. Whilethe signal coupler may perform sequential measurements at multiplereference planes (e.g., by measuring a first reference plane,reconfiguring a termination in the signal coupler, and then measuring asecond reference plane associated with the reconfigured termination),sequential measurements are impractical due to the dynamic nature of thesignal. To mitigate these issues and to allow concurrentcharacterization of multiple reference planes along the signal path,multi-coupler circuitry may be disposed along the signal path.

FIG. 2 is a diagram showing how device 10 may include signaltransmission circuitry 35 having multi-coupler circuitry forconcurrently characterizing multiple reference planes along the signalpath. As shown in FIG. 2 , signal transmission circuitry 35 may includea signal source 36 having a source impedance and a source power. Signalsource 36 may be coupled to output node N over signal path 40. Outputnode N may be coupled to an output load 42 (e.g., over a portion ofsignal path 34). Signal source 36 may transmit signals to output node Nover signal path 40.

Signal path 40 may sometimes also be referred to herein as signal line40, signal conductor 40, or signal chain 40. Signal transmissioncircuitry 35 may, as one example, form a part of wireless circuitry 24(FIG. 1 ). In this example, signal source 36 may be a power amplifier(e.g., in transmitter 28 of FIG. 1 ), signal path 40 may be aradio-frequency transmission line (e.g., a signal conductor ofradio-frequency transmission line 32 of FIG. 1 ), and output load 42 maybe a corresponding antenna (e.g., antenna 30 of FIG. 1 ). Signal source36 may therefore sometimes be referred to herein as power amplifier (PA)36 and signal path 40 may sometimes also be referred to herein astransmission line 40. Power amplifier 36 may transmit radio-frequencysignals over signal path 40 and antenna 30. While implementations inwhich signal transmission circuitry 35 forms a part of wirelesscircuitry 24 for transmitting radio-frequency signals over antenna 30are described herein as an example, signal transmission circuitry 35may, in general, include any desired passive signal transmissioncircuitry in device 10 in addition to signal source 36 (e.g., fortransmitting signals at any frequencies between different boards,packages, nodes, chips, integrated circuits, processors, components,accessories, devices such as device 10, etc.). The systems and methodsfor measuring output power levels and otherwise characterizing theperformance of signal path 40 when signal transmission circuitry 35forms a part of wireless circuitry 24 for transmitting radio-frequencysignals over antenna 30 as described herein may be similarly applied inany of these signal transmission contexts.

Output load 42 may have an impedance. The impedance of output load 42may vary (e.g., at a given frequency) due to changes in environmentalconditions around output load 42, such as when an external object 37approaches the output load. In examples where output load 42 is anantenna, external object 37 (e.g., a user's hand or other body part) mayexternally load the antenna, causing the antenna to become detuned andproducing an impedance discontinuity between output node N and signalpath 40. This impedance discontinuity may cause a relatively largeamount of the transmitted signal power to be reflected back towardspower amplifier 36 from output node N, reducing the overall efficiencyof the antenna. By measuring a power wave of the signal at node N,signal transmission circuitry 35 may measure (e.g., detect) theimpedance of output load 42 (e.g., as subject to external loading byexternal object 37) and may use this information to adjust impedancematching circuitry for the antenna, to adjust tuning of the antenna, toreduce transmit power level of power amplifier 36 (e.g., to comply withregulatory limits on radio-frequency energy exposure or absorption),and/or to perform any other desired operations to characterize theperformance of output load 42 or to mitigate loading by external object37. In general, the impedance of output load 42 is a complex value andmay be characterized by the complex reflection coefficient Γ_(L).Reflection coefficient Γ_(L) may have a relatively high magnitude when arelatively large impedance discontinuity at output node N causes arelatively large amount of the transmitted signal power to be reflectedback towards power amplifier 36, for example.

In practice, it may be desirable to measure the signal at multipledifferent points (referred to herein as reference planes R) along signalpath 40. There may, for example, be one or more circuit blocks Binterposed along signal path 40 between signal source 36 and output nodeN (e.g., circuit blocks for performing one or more functions of device10 that may or may not be associated with the transmission of signals atoutput node N). In the example of FIG. 2 , there are at least fourcircuit blocks B1, B2, B3, and B4 disposed along signal path 40. This isillustrative and, in general, there may be only one circuit block B1,two circuit blocks B1 and B2, three circuit blocks B1, B2, and B3, ormore than four circuit blocks B disposed along signal path 40. Circuitblocks B may include, for example, passive devices, capacitors,inductors, resistors, impedance matching circuitry, antenna tuningcircuitry, routing circuitry, transmission lines, switches, filters,other couplers coupled to radio-frequency front end circuitry,transmit/receive (TR) switches connected to other radio-frequency frontend circuitry, etc.

The performance of one or more circuit blocks B may be characterized bymeasuring the power wave of the signal along signal path 40 at referenceplanes located before, after, and/or between circuit blocks B. Forexample, at a first reference plane R1 between circuit blocks B1 and B2,a second reference plane R2 between circuit blocks B2 and B3, areference plane R3 between circuit blocks B3 and B4, and/or at a fourthreference plane R5 after circuit block B4. The overall performance ofsignal path may be characterized by concurrently measuring the powerwave of the signal along signal path 40 at two or more of referenceplanes R1-R4. One or more of reference planes R1-R4 may be locatedelsewhere along signal path 40 if desired (e.g., at the output of signalsource 36, at the input of circuit block B1, within circuit blocks B1,B2, B3, and/or B4, etc.).

Signal transmission circuitry 35 may include signal coupler circuitryinterposed on signal path between signal source 36 and circuit block B1such as multi-coupler circuitry 38. If desired, one or more circuitblocks B may be interposed on signal path 40 between signal source 46and multi-coupler circuitry 38. Multi-coupler circuitry 38 may have afirst port P1 communicably coupled to the output of signal source 36over a first portion of signal path 40 and may have a second port P2communicably coupled to node N over a second portion of signal path 40(e.g., via circuit blocks B1-B4). Multi-coupler circuitry 38 may includetwo or more signal couplers. Each signal coupler in multi-couplercircuitry 38 may be used to concurrently measure a signal along signalpath 40 (e.g., a power wave, forward wave, reverse wave, etc.) within arespective one of reference planes R1-R4. For example, multi-couplercircuitry 38 may include a first signal coupler that measures the signalat reference plane R1, a second signal coupler that concurrentlymeasures the signal at reference plane R2, a third signal coupler thatconcurrently measures the signal at reference plane R3, and/or a fourthsignal coupler that concurrently measures the signal at reference planeR4. Multi-coupler circuitry 38 may include more than four signalcouplers when more than four reference planes are concurrently measured.Each signal coupler in multi-coupler circuitry 38 may overlap the samesegment of signal path 40 or, if desired, may overlap differentrespective segments of signal path 40. Multi-coupler circuitry 38 mayalso include power detectors, voltage detectors, and/or signal receiversthat are used to perform measurements using the two or more signalcouplers in multi-coupler circuitry 38. Each signal coupler may includeone or two corresponding terminations.

Multi-coupler circuitry 38 may receive control signals CTRL (e.g., fromcontrol circuitry 14 of FIG. 1 ). If desired, control signals CTRL maycontrol switches in one or more of the signal couplers to controlwhether the signal coupler measures a forward wave or a reverse wavewithin its corresponding reference plane. Control signals CTRL mayadditionally or alternatively adjust an impedance of one or more of theterminations for one or more of the signal couplers in multi-couplercircuitry 38 to dynamically adjust the location of the correspondingreference plane R over time (e.g., the location of reference planes R1,R2, R3, and/or R4 along signal path 40 may be adjusted over time). Themeasurements of the signal concurrently gathered from reference planesR1, R2, R3, and/or R4 may be used to characterize the performance of oneor more of circuit blocks B1-B4, signal source 36, output load 42,and/or to characterize the performance of signal path 40 as a whole. Ifdesired, the characterized performance may be used to performadjustments to signal source 36, one or more of circuit blocks B1-B4,and/or output load 42 (e.g., to compensate for any non-idealitiesdetected along signal path 40 via concurrent measurement of two or moreof reference planes R1-R4).

FIG. 3 is a circuit diagram showing one example in which multi-couplercircuitry 38 includes two signal couplers for concurrently measuring thesignal along transmission line 40 at (within) reference planes R1 andR2. As shown in FIG. 3 , multi-coupler circuitry 38 may include a firstsignal coupler 46-1 and a second signal coupler 46-2. Signal couplers46-1 and 46-2 may sometimes be collectively referred to herein asmulti-coupler 44 or dual coupler 44. Signal couplers 46-1 and 46-2 mayinclude transmission line structures, inductive structures, capacitivestructures, transformers, or any other desired type of structures thatcouple signal off of signal path 40 for further processing (e.g., signalcouplers 46-1 and 46-2 may be transmission line couplers, inductivecouplers, capacitive couplers, etc.). Signal couplers 46-1 and 46-2 mayshare ports P1 and P2 of multi-coupler circuitry 38.

During signal transmission, signal source 36 may transmit signals (e.g.,radio-frequency signals) on signal path 40. These signals may sometimesbe referred to as forward wave (FW) signals. The energy of the FWsignals into port P1 may be characterized by coefficient a₁ (e.g., in afour-port network model of the system). The energy (power wave) of theFW signals out of port P2 may be characterized by a coefficient b₂(e.g., the magnitude of the signal wave of the FW signals in thefour-port network model). During signal transmission, some of the FWsignals will reflect off of output node N or other components alongsignal path 40 (e.g., circuit blocks B1 or B2) and back towardsmulti-coupler circuitry 38 (e.g., due to impedance discontinuities alongsignal path 40 at circuit blocks B1 or B2 or at node N). These reflectedsignals may sometimes be referred to as reverse wave (RW) signals.

In the implementation of FIG. 3 , signal coupler 46-1 and signal coupler46-2 are switch-configured couplers that are able to measure the FWsignals and the RW signals along signal path 40. As shown in FIG. 3 ,signal coupler 46-2 may have a third port P3 and a fourth port P4 thatare communicably coupled to receiver (RX) 56-2. Port P3 represents thecoupled node of signal coupler 46-2 and may therefore sometimes bereferred to herein as coupled node P3 or coupled node port P3. Port P4represents the isolated node of signal coupler 46-2 (e.g., the port/nodeisolated from the signal source) and may therefore sometimes be referredto herein as isolated node P4 or isolated node port P4. Signal coupler46-2 may have switching circuitry such as switches SW5, SW6, SW7, andSW8 (sometimes referred to herein as a first set of switches or firstswitching circuitry). Switch SW6 may couple port P3 to receiver 56-2.Switch SW7 may couple port P4 to receiver 56-2. Switch SW5 may coupleport P3 to a termination impedance such as coupled node termination 48.Switch SW8 may couple port P4 to a termination impedance such asisolated node termination 50.

Coupled node termination 48 may have a complex impedance characterizedby a corresponding complex reflection coefficient Γ_(T,COUP2). Couplednode termination 48 may include one or more resistive, capacitive,inductive, and/or switching components that configure coupled nodetermination 48 to exhibit the impedance characterized by reflectioncoefficient Γ_(T,COUP2). Isolated node termination 50 may have a compleximpedance characterized by a corresponding complex reflectioncoefficient Γ_(T,ISOL2). Isolated node termination 50 may include one ormore resistive, capacitive, inductive, and/or switching components thatconfigure isolated node termination 50 to exhibit the impedancecharacterized by reflection coefficient Γ_(T,ISOL2).

Receiver 56-2 may include a power detector, voltage detector, phasedetector, mixer, and/or any other desired circuitry for receiving and/ormeasuring signals coupled off of signal path 40 by signal coupler 46-2.Switches SW5, SW6, SW7, and SW8 (e.g., the first set of switches) mayhave a first state in which switch SW6 is turned on to couple port P3 toreceiver 56-2, switch SW5 is turned off to decouple coupled nodetermination 48 from port P3, switch SW7 is turned off to decouple portP4 from receiver 56-2, and switch SW8 is turned on to couple port P4 toisolated node termination 50. Switches SW5, SW6, SW7, and SW8 (e.g., thefirst set of switches) may also have a second state in which switch SW6is turned off to decouple port P3 from receiver 56-2, switch SW5 isturned on to couple coupled node termination 48 to port P3, switch S7 isturned on to couple port P4 to receiver 56-2, and switch SW8 is turnedoff to decouple port P4 from isolated node termination 50.

When described herein as “turned off,” “deactivated,” or “opened” agiven switch SW may form a very high impedance or very low conductancethrough the switch (e.g., an impedance that exceeds a thresholdimpedance value or a conductance that is less than a thresholdconductance value). When described herein as “turned on,” “activated,”or “closed” a given switch SW may form a very low impedance or very highconductance through the switch (e.g., an impedance that is less than athreshold impedance value or a conductance that exceeds a thresholdconductance value). As an example, switches SW may each be formed usingtransistors having source, drain, and gate terminals. Each switch may beclosed or “turned on” by asserting a gate voltage provided to the gateterminal to provide an electrical connection between its source anddrain terminals. Similarly, each switch may be opened or “turned off” bydeasserting the gate voltage to provide electrical isolation between itssource and drain terminals.

In the first state, signal coupler 46-2 and receiver 56-2 may perform,gather, or measure FW signals (e.g., FW measurements). Signal coupler46-2 may couple some of the FW signals off of signal path 40 and maypass the FW signals (as well as a portion of the RW signal bouncing offthe isolated node termination) to receiver 56-2 via port P3 and switchSW6. Receiver 56-2 may measure the amplitude and/or phase of the FWsignals. In the second state, signal coupler 46-2 and receiver 56-2 mayperform, gather, or measure RW signals (e.g., RW measurements). Signalcoupler 46-2 may couple some of the RW signals off of signal path 40 andmay pass the RW signals to receiver 56-2 via port P4 and switch SW7.Receiver 56-2 may measure the amplitude and/or phase of the RW signals.

The impedance of coupled node termination 48 and the impedance ofisolated node termination may be selected to configure signal coupler46-2 and receiver 56-2 to measure the FW signal and/or the RW signalwithin a corresponding reference plane R2 along signal path 40. In theexample of FIG. 3 , reference plane R2 is located after circuit block B2but may, in general, be located anywhere along signal path 40 betweensignal source 36 and output node N. If desired, reference plane R2 maybe located at the output of signal source 36 or at node N. Controlcircuitry 14 may process the FW signal measurements and/or the RW signalmeasurements performed using signal coupler 46-2 and receiver 56-2 tocharacterize (e.g., identify, determine, detect, compute, calculate,measure, etc.) the performance of signal path 40 (e.g., in conveying thesignals) at or near the location of reference plane R2 (e.g., tocharacterize the performance of circuit block B2, to characterize theperformance of output load 42, to characterize the performance of signalsource 36, etc.). If desired, the control circuitry may characterize(e.g., identify, determine, detect, compute, calculate, measure, etc.)the impedance of signal path 40 at reference plane R2 (e.g., using aratio of the FW and RW measurements) and/or the forward power wave atreference plane R2 (e.g., using expressions involving the FWmeasurements and impedances). Control circuitry 14 may use the FWmeasurements, RW measurements, characterized performance, impedance,and/or delivered power for performing subsequent processing operations,for example.

Because signal coupler 46-1 in multi-coupler circuitry 38 is separatefrom signal coupler 46-2 and includes different impedance terminationsthan the impedance terminations of signal coupler 46-2, signal coupler46-1 may be used to concurrently characterize the signal along signalpath 40 within reference plane R1, which is located at a differentportion of signal path 40 than reference plane R2. As shown in FIG. 3 ,signal coupler 46-2 may have a fifth port P5 and a sixth port P6 thatare communicably coupled to receiver (RX) 56-1 (e.g., multi-coupler 44may have six ports P1-P6). Signal coupler 46-1 may partially orcompletely overlap the same portion of signal path 40 as signal coupler46-2 (and signal couplers 46-1 and 46-2 may thereby couple signals offthe same portion of signal path 40) or may be non-overlapping withrespect to signal coupler 46-2.

Port P5 represents the coupled node of signal coupler 46-1 and maytherefore sometimes be referred to herein as coupled node P5. Port P6represents the isolated node of signal coupler 46-1 (e.g., the port/nodeisolated from the signal source) and may therefore sometimes be referredto herein as isolated node P6. Signal coupler 46-1 may have switchingcircuitry such as switches SW1, SW2, SW3, and SW4 (sometimes referred toherein as a second set of switches or second switching circuitry).Switch SW2 may couple port P5 to receiver 56-1. Switch SW3 may coupleport P6 to receiver 56-1. Switch SW1 may couple port P5 to a terminationimpedance such as coupled node termination 52. Switch SW4 may coupleport P6 to a termination impedance such as isolated node termination 54.

Coupled node termination 52 may have a complex impedance characterizedby a corresponding complex reflection coefficient Γ_(T,COUP1) that isdifferent from the complex reflection coefficient Γ_(T,COUP2) of thecoupled node termination 48 of signal coupler 46-2. Coupled nodetermination 52 may include one or more resistive, capacitive, inductive,and/or switching components that configure coupled node termination 52to exhibit the impedance characterized by reflection coefficientΓ_(T,COUP1). Isolated node termination 54 may have a complex impedancecharacterized by a corresponding complex reflection coefficientΓ_(T,ISOL1) that is different from the complex reflection coefficientΓ_(T,COUP1) of the coupled node termination 52 of signal coupler 46-1.Isolated node termination 54 may include one or more resistive,capacitive, inductive, and/or switching components that configureisolated node termination 54 to exhibit the impedance characterized byreflection coefficient Γ_(T,ISOL1).

Receiver 56-1 may be the same receiver as the receiver 56-2 used bysignal coupler 46-2 or may be a separate receiver. Receiver 56-1 mayinclude a power detector, voltage detector, phase detector, and/or anyother desired circuitry for receiving and/or measuring signals coupledoff of signal path 40 by signal coupler 46-1. Switches SW1, SW2, SW3,and SW4 (e.g., the second set of switches) may have a first state inwhich switch SW2 is turned on to couple port P5 to receiver 56-1, switchSW1 is turned off to decouple coupled node termination 52 from port P5,switch SW3 is turned off to decouple port P6 from receiver 56-1, andswitch SW4 is turned on to couple port P6 to isolated node termination54. Switches SW1, SW2, SW3, and SW4 (e.g., the second set of switches)may also have a second state in which switch SW2 is turned off todecouple port P5 from receiver 56-1, switch SW1 is turned on to couplecoupled node termination 52 to port P5, switch SW3 is turned on tocouple port P6 to receiver 56-1, and switch SW4 is turned off todecouple port P6 from isolated node termination 54. Control circuitry 14(FIG. 1 ) may provide control signals (e.g., control signals CTRL ofFIG. 2 ) to multi-coupler circuitry 38 that place switches SW1-SW4 intoa selective one of the first or second states. The control signals mayalso independently place SW5-SW8 of signal coupler 46-2 into a selectedone of the first or second states (e.g., signal coupler 46-1 may betoggled between states independent of signal coupler 46-2) forindependently and concurrently characterizing reference planes R1 andR2.

In the first state, signal coupler 46-1 and receiver 56-1 may perform,gather, or measure FW signals (e.g., FW measurements). Signal coupler46-1 may couple some of the FW signals off of signal path 40 and maypass the FW signals (as well as a portion of the RW signal bouncing offisolated node termination 54) to receiver 56-1 via coupled node P5 andswitch SW2. Receiver 56-1 may measure the amplitude and/or phase of theFW signals. In the second state, signal coupler 46-1 and receiver 56-1may perform, gather, or measure RW signals (e.g., RW measurements).Signal coupler 46-1 may couple some of the RW signals off of signal path40 and may pass the RW signals to receiver 56-1 via port P6 and switchSW3. Receiver 56-1 may measure the amplitude and/or phase of the RWsignals.

The impedance of coupled node termination 52 and the impedance ofisolated node termination 54 may be selected to configure signal coupler46-1 and receiver 56-1 to measure the FW signal and/or the RW signalwithin the corresponding reference plane R1 located elsewhere alongsignal path 40 than reference plane R2 of signal coupler 46-2. In theexample of FIG. 3 , reference plane R1 is located between circuit blocksB1 and B2 but may, in general, be located anywhere along signal path 40between signal source 36 and output node N. If desired, reference planeR1 may be located at the output of signal source 36 or at node N.Control circuitry 14 may process the FW signal measurements and/or theRW signal measurements performed using signal coupler 46-2 and receiver56-2 to characterize (e.g., identify, determine, detect, compute,calculate, measure, etc.) the performance of signal path 40 (e.g., inconveying the signals) at or near the location of reference plane R1(e.g., to characterize the performance of circuit block B2, tocharacterize the performance of output load 42, to characterize theperformance of signal source 36, etc.). If desired, the controlcircuitry may characterize (e.g., identify, determine, detect, compute,calculate, measure, etc.) the impedance of signal path 40 at referenceplane R1 (e.g., using a ratio of the FW and RW measurements) and/or thedelivered power at reference plane R1 (e.g., using expressions involvingthe FW measurements and impedances). Control circuitry 14 may use the FWmeasurements, RW measurements, characterized performance, impedance,and/or delivered power for performing subsequent processing operations,for example.

If desired, control circuitry 14 may process the FW signal measurementsand/or the RW signal measurements for both reference plane R1 (asgathered using signal coupler 46-1) and reference plane R2 (as gatheredusing signal coupler 46-2) to characterize the performance of the samecomponent along signal path 40 (e.g., circuit block B2, which is betweenreference planes R1 and R2). Multi-coupler circuitry 38 may concurrentlycharacterize two different points along signal path 40 (reference planesR1 and R2), which allows control circuitry 14 to have more completeknowledge of the operation and performance of signal path 40 than inexamples where only a single point or reference plane is characterizedor measured.

Reference plane R1 and/or reference plane R2 may be adjustable. Forexample, a control signal CTRLB may be provided to coupled nodetermination 48 and isolated node termination 50 of signal coupler 46-2(e.g., within control signals CTRL of FIG. 2 ). Control signal CTRLB mayadjust switching circuitry, inductance(s), resistance(s), and/orcapacitance(s) and thus the impedances of coupled node termination 48and/or isolated node termination 50 to dynamically adjust the locationof reference plane R2 along signal path 40 over time, as shown by arrow60 (e.g., to adjust the location along signal path 40 at which signalcoupler 46-2 measures the FW and/or RW). Additionally or alternatively,a control signal CTRLA may be provided to coupled node termination 52and isolated node termination 54 of signal coupler 46-1 (e.g., withincontrol signals CTRL of FIG. 2 ). Control signal CTRLA may adjustswitching circuitry, inductance(s), resistance(s), and/or capacitance(s)and thus the impedances of coupled node termination 52 and/or isolatednode termination 54 to dynamically adjust the location of referenceplane R1 along signal path 40 over time, as shown by arrow 58 (e.g., toadjust the location along signal path 40 at which signal coupler 46-2measures the FW and/or RW). This may allow control circuitry 14 toconcurrently measure and characterize multiple reference planes atdifferent locations along signal path 40 overtime (e.g., to allow for acomplete and robust characterization of signal path 40). The controlsignal(s) may also be used to adjust the termination to the correctvalue in the event that there is some corner variation or temperaturevariation, which would affect the coupler and circuit blocks B1-B4.

The example of FIG. 3 in which signal coupler 46-1 and signal coupler46-2 both measure FW and RW signals is illustrative. If desired, signalcoupler 46-2 may be simplified to only measure power at itscorresponding reference plane R2. FIG. 4 is a circuit diagram showingone example of how signal coupler 46-2 may be simplified to only measurepower (e.g., power wave) at its corresponding reference plane R2.

As shown in FIG. 4 , port P3 of signal coupler 46-2 may be coupled to apower detector such as power detector (PDECT) 62. Port P4 of signalcoupler 46-2 may be coupled to a termination impedance such as isolatednode termination 64 (e.g., the first set of switches SW5-SW8 in FIG. 3may be omitted). Isolated node termination 64 may have a compleximpedance characterized by a corresponding complex reflectioncoefficient Γ_(T2). Isolated node termination 64 may include one or moreresistive, capacitive, inductive, and/or switching components thatconfigure isolated node termination 64 to exhibit the impedancecharacterized by reflection coefficient Γ_(T2). The impedance ofisolated node termination 64 may be set to configure signal coupler 46-2to exhibit reference plane R2. If desired, control signal CTRLB mayadjust the impedance of isolated node termination 64 to shift thelocation of reference plane R2 along signal path 40 (as shown by arrow60). Power detector 62 may measure voltage at port P3 and/or the powerassociated with the voltage at port P3 (e.g., power detector 62 mayconvert a radio-frequency voltage waveform into a DC voltage). Controlcircuitry 14 (FIG. 1 ) may process the voltage and/or power measured bypower detector 62 to measure (e.g., estimate, determine, identify,compute, calculate, generate, sense, etc.) the signal or power wave atreference plane R2. Signal coupler 46-1 may measure the FW signal and/orthe RW signal at reference plane R1 (e.g., due to the presence ofswitches SW1-SW4) concurrently with and independently from measurementof power at reference plane R2 by signal coupler 46-2.

The example of FIG. 4 in which only signal coupler 46-2 includes a powerdetector to measure the power (e.g., power wave) at its correspondingreference plane R2 is illustrative. If desired, signal coupler 46-1 mayalso include a power detector to measure the power wave at itscorresponding reference plane R1. FIG. 5 is a circuit diagram showingone example of how signal coupler 46-1 and signal coupler 46-2 may bothinclude power detectors.

As shown in FIG. 5 , port P5 of signal coupler 46-1 may be coupled to apower detector such as power detector (PDECT) 66. Port P6 of signalcoupler 46-1 may be coupled to a termination impedance such as isolatednode termination 68 (e.g., the second set of switches SW1-SW4 of FIGS. 3and 4 may be omitted). Isolated node termination 68 may have a compleximpedance characterized by a corresponding complex reflectioncoefficient Γ_(T1). Isolated node termination 68 may include one or moreresistive, capacitive, inductive, and/or switching components thatconfigure isolated node termination 68 to exhibit the impedancecharacterized by reflection coefficient Γ_(T1). The impedance ofisolated node termination 68 may be set to configure signal coupler 46-1to exhibit reference plane R1. If desired, control signal CTRLA mayadjust the impedance of isolated node termination 68 to shift thelocation of reference plane R1 along signal path 40 (as shown by arrow60). Power detector 62 may measure voltage at port P5 and/or the powerassociated with the voltage at port P5 (e.g., power detector 66 mayconvert a radio-frequency voltage waveform into a DC voltage). Controlcircuitry 14 (FIG. 1 ) may process the voltage and/or power measured bypower detector 62 to measure (e.g., estimate, determine, identify,compute, calculate, generate, sense, etc.) the signal or power wave atreference plane R1. Signal coupler 46-1 may measure power at referenceplane R1 concurrently with and independently from measurement of powerat reference plane R2 by signal coupler 46-2.

If care is not taken, measurements made using multi-coupler 44 mayundesirably vary as the reflection coefficient of one or more componentsalong signal path 40 varies. These variations can reduce the accuracy ofthe measurements made by power detectors 62 and/or 66, thereby reducingaccuracy in how device 10 characterizes the performance of signal path40. To mitigate these issues, isolated node termination 64 of FIGS. 4and 5 may be configured to exhibit a particular complex impedance thatis characterized by reflection coefficient Γ_(T2)=Γ_(TSSI,2). Similarly,isolated node termination 68 of FIG. 5 may be configured to exhibit aparticular complex impedance that is characterized by reflectioncoefficient Γ_(T1)=_(TSSI,1). In other words, isolated node termination64 may include capacitive, resistive, switching, inductive, and/or othercircuit components arranged in a manner (e.g., in series, in parallel,with respect to ground, etc.) that configure isolated node termination64 to exhibit a reflection coefficient Γ_(T,2)=Γ_(TSSI,2). Similarly,isolated node termination 68 may include capacitive, resistive,switching, inductive, and/or other circuit components arranged in amanner (e.g., in series, in parallel, with respect to ground, etc.) thatconfigure isolated node termination 68 to exhibit a reflectioncoefficient Γ_(T,1)=Γ_(TSSI,1).

The reflected and incident power waves at the ports signal coupler 46-1may be characterized by sixteen scattering parameters or S-parametersfor a fixed frequency, which are complex numbers associated with thefour-port network model of signal coupler circuitry 38 (e.g., where thefirst (input) port is defined by port P1, the second (output) port isdefined by port P2, the third port is defined by port P5, and the fourthport is defined by port P6). The S-parameters include: S₁₁ (e.g., areflection coefficient at the input port), S₁₂ (e.g., characterizingreverse voltage gain), S₁₃, S₁₄, S₂₁ (e.g., characterizing forwardvoltage gain), S₂₂ (e.g., a reflection coefficient at the output port),S₂₃, S₂₄, S₃₁, S₃₂, S₃₃, S₃₄, S₄₁, S₄₂, S₄₃, and S₄₄. The circuitcomponents of isolated node termination 68 may be selected such thatisolated node termination 68 exhibits an impedance characterized by areflection coefficient Γ_(T1)=Γ_(TSSI,1), where Γ_(TSSI,1) is given byequation 1.

$\begin{matrix}{\Gamma_{{TSSI},1} = \frac{{S_{21}S_{32}} - {S_{22}S_{31}}}{\begin{matrix}{{S_{21}\left( {{S_{32}S_{44}} - {S_{34}S_{42}}} \right)} + {S_{22}\left( {{S_{34}S_{41}} - {S_{31}S_{44}}} \right)} +} \\{S_{24}\left( {{S_{31}S_{42}} - {S_{32}S_{41}}} \right)}\end{matrix}}} & (1)\end{matrix}$

In other words, reflection coefficient Γ_(TSSI,1) is a function of eachof the S-parameters (with respect to reference plane R1) except for S₁₁,S₁₂, S₁₃, S₁₄, S₂₃, S₃₃, and S₄₃. The numerator of reflectioncoefficient Γ_(TSSI,1) is a function of S₂₁, S₃₂, S₂₂, and S₃₁ (forreference plane R1). The denominator of reflection coefficientΓ_(TSSI,1) is a function of S₂₁, S₃₂, S₄₄, S₃₄, S₄₂, S₂₂, S₄₁, S₃₁, S₂₄,and S₄₂ (for reference plane R1). This configures the voltage at port P5and into power detector 66 and its corresponding power to track theamplitude (magnitude) of the FW signal (power wave) at reference planeR1 to within a constant value that does not change as the impedance atreference plane R1 changes over time. Similarly, for signal coupler46-2, port P3 may take the place of port P5 and port P4 may take theplace of port P6 in the four-port network model, and isolated nodetermination 64 may have an impedance selected such that isolated nodetermination 64 exhibits an impedance characterized by a reflectioncoefficient Γ_(T2)=Γ_(TSSI,2), where Γ_(TSSI,2) is given by the rightside of equation 1 and where the scattering parameters in equation 1 aretaken with respect to reference plane R2. This configures the voltage atport P3 and into power detector 62 and its corresponding power to trackthe amplitude (magnitude) of the FW signal (power wave) at referenceplane R2 to within a constant value that does not change as theimpedance at reference plane R2 changes over time.

If desired, multi-coupler 44 of FIGS. 3-5 may include one or moreadditional signal couplers 46 for characterizing one or more referenceplanes (e.g., reference planes R3 and/or R4 of FIG. 2 ) in addition toreference planes R1 and R2. It may be desirable to maximize isolationbetween each of the signal couplers 46 in multi-coupler 44 (e.g., toallow for concurrent and independent measurement of multiple referenceplanes along signal path 40). Minimizing the coupling factors of thesignal couplers may help to maximize isolation between the signalcouplers. If desired, isolation between the signal couplers may bemaximized by distributing the signal couplers across multiplemetallization layers on a substrate.

FIG. 6 is a cross-sectional side view showing one example of how signalcouplers 46 may be distributed across multiple metallization layers on asubstrate. As shown in FIG. 6 , multi-coupler 44 may be disposed on asubstrate 70. Substrate 70 may include multiple stacked dielectriclayers 72 (e.g., at least a first dielectric layer 72-1, a seconddielectric layer 72-2, and a third dielectric layer 72-3). Dielectriclayers 72 may be, for example, layers of rigid or flexible printedcircuit board material (e.g., polyimide), ceramic, plastic, or othermaterials.

Multi-coupler 44 may include a first metallization layer patterned ontodielectric layer 72-1, a second metallization layer patterned ontodielectric layer 72-2, and a third metallization layer patterned ontodielectric layer 72-3. The first metallization layer may includeconductive traces 78. The second dielectric layer may include conductivetraces 74, 80, and/or 82. The third metallization layer may includeconductive traces 76. Conductive traces 74 may form signal path 40(e.g., the signal conductor of signal path 40 in implementations wheresignal path 40 is a radio-frequency transmission line). Conductivetraces 76 may form signal coupler 46-1 and conductive traces 78 may formsignal coupler 46-2 of multi-coupler 44. Forming signal couplers 46-1and 46-2 from metallization layers on opposing sides of themetallization layer used to form signal path 40 in this way may serve tomaximize isolation between signal couplers 46-1 and 46-2, which mayallow for accurate and concurrent measurement of reference planes R1 andR2 along signal path 40.

If desired, conductive traces 80 may be used to form a third signalcoupler and/or conductive traces 82 may be used to form a fourth signalcoupler in multi-coupler 44. An arrangement of this type may allowconcurrent characterization of up to four reference planes along signalpath 40 (e.g., reference planes R1-R4 of FIG. 2 ) with maximum isolationbetween the signal couplers and while occupying a minimal amount ofspace in device 10. The example of FIG. 6 in which conductive traces 76and 78 are used to form respective signal couplers 46-1 and 46-2 isillustrative. In general, any of conductive traces 76-82 may be used toform signal couplers 46-1 and 46-2 (e.g., signal coupler 46-1 may beformed from conductive traces 80 whereas signal coupler 46-2 is formedfrom conductive traces 82, signal coupler 46-1 may be formed fromconductive traces 76 whereas signal coupler 46-2 is formed fromconductive traces 80, etc.).

FIG. 7 is a flow chart of illustrative operations that may be performedby device 10 for gathering and processing measurements usingmulti-coupler circuitry 38 of FIGS. 3-6 . At operation 84, signal source36 may transmit signals on signal path 40. Each signal coupler 46 inmulti-coupler circuitry 38 may concurrently couple some of the signalsoff of signal path 40 via its respective coupled node (port). Eachsignal coupler may concurrently (e.g., simultaneously) measure a powerwave (e.g., using a corresponding power detector) or FW/RW signals(e.g., using a corresponding receiver 56) at a respective referenceplane R (e.g., at a respective point) along signal path 40. Thereference planes for each signal coupler are determined by thetermination(s) of the signal coupler. Using different signal couplerswith different terminations within multi-coupler circuitry 38 may allowdifferent reference planes to be concurrently measured. Distributing thesignal couplers across metallization layers (e.g., as shown in FIG. 6 )may maximize isolation between the signal couplers to help the signalcouplers perform accurate measurements.

At operation 86, control circuitry 14 may perform any desired operationsbased on the measured power or signal waves measured using multi-couplercircuitry 38. For example, control circuitry 14 may use the measurementsconcurrently gathered from each of the reference planes to identify(e.g., characterize, compute, calculate, determine, detect, etc.) theimpedance at one or more of the reference planes, to identify themagnitude of power wave at one or more of the reference planes, toidentify the linearity of one or more components (e.g., circuit blocksB) along signal path 40, to identify the linearity or othercharacteristics of signal source 36 (e.g., along with measurements tothe input of signal source 36), to characterize the overall performanceof some or all of signal path 40 (e.g., of one or more circuit blocksB), to detect external object 37 (FIG. 2 ), to detect non-idealities(e.g., deviations from nominal or expected performance) or errors in oneor more of the components (e.g., circuit blocks B) along signal path 40,to detect when a mechanical fault of packaging issue is present alongsignal path 40 (e.g., in examples where signal path 40 extends betweenintegrated circuits, chips, circuit boards, or packages), to issue analert when a non-ideality or error is detected, to flag some or all ofsignal path 40 for debugging or repair when a non-ideality or error isdetected, etc. If desired, control circuitry 14 may adjust the operationof one or more components along signal path 40 based on one or more ofthese quantities and/or the measurements concurrently gathered from eachof the reference planes. For example, control circuitry 14 may adjustthe transmit power level of signal source 36, may adjust the operationof one or more circuit blocks B, may adjust how one or more circuitblocks B interact with the signals transmitted along signal path 40, mayadjust the tuning or impedance matching of an antenna coupled to outputnode N, may perform operations to mitigate non-idealities or errorsdetected along signal path 40, etc.

At optional operation 88, control circuitry 14 (FIG. 1 ) may use controlsignals CTRL (FIG. 2 ) to dynamically adjust, change, or shift thelocation of one or more of the reference planes R of multi-couplercircuitry 38. The control signals may, for example, adjust the impedanceof one or more terminations of one or more of the signal couplers inmulti-coupler circuitry 38. Processing may subsequently loop back tooperation 84 via path 90 to concurrently gather measurements from theupdated reference plane(s). In this way, control circuitry 14 mayconcurrently measure and characterize multiple reference planes alongsignal path 40 and may adjust the reference planes to characterize someor all of the signal path over time. Operation 88 may be omitted ifdesired. In these implementations, processing may loop back to operation84 from operation 86.

Device 10 may gather and/or use personally identifiable information. Itis well understood that the use of personally identifiable informationshould follow privacy policies and practices that are generallyrecognized as meeting or exceeding industry or governmental requirementsfor maintaining the privacy of users. In particular, personallyidentifiable information data should be managed and handled so as tominimize risks of unintentional or unauthorized access or use, and thenature of authorized use should be clearly indicated to users.

The methods and operations described above in connection with FIGS. 1-7may be performed by the components of device 10 using software,firmware, and/or hardware (e.g., dedicated circuitry or hardware).Software code for performing these operations may be stored onnon-transitory computer readable storage media (e.g., tangible computerreadable storage media) stored on one or more of the components ofdevice 10 (e.g., storage circuitry 16 of FIG. 1 ). The software code maysometimes be referred to as software, data, instructions, programinstructions, or code. The non-transitory computer readable storagemedia may include drives, non-volatile memory such as non-volatilerandom-access memory (NVRAM), removable flash drives or other removablemedia, other types of random-access memory, etc. Software stored on thenon-transitory computer readable storage media may be executed byprocessing circuitry on one or more of the components of device 10(e.g., processing circuitry 18 of FIG. 1 , etc.). The processingcircuitry may include microprocessors, central processing units (CPUs),application-specific integrated circuits with processing circuitry, orother processing circuitry.

The foregoing is illustrative and various modifications can be made tothe described embodiments. The foregoing embodiments may be implementedindividually or in any combination.

What is claimed is:
 1. An electronic device comprising: a signal source;an output load coupled to the signal source over a signal path, thesignal source being configured to transmit a signal to the output loadover the signal path; a first signal coupler coupled to the signal pathand having a first termination with a first impedance; and a secondsignal coupler coupled to the signal path and having a secondtermination with a second impedance different from the first impedance.2. The electronic device of claim 1, further comprising: one or moreprocessors configured to measure a power wave at a first reference planealong the signal path using the first signal coupler and configured toconcurrently measure a power wave at a second reference plane along thesignal path using the second signal coupler, the second reference planebeing different from the first reference plane.
 3. The electronic deviceof claim 1, wherein the first signal coupler comprises: a first couplednode; a first isolated node; a third termination with a third impedance;a first receiver; and first switching circuitry that switchably couplesthe first coupled node and the first isolated node to the firstreceiver, the first termination, and the third termination.
 4. Theelectronic device of claim 3, wherein the second signal couplercomprises: a second coupled node; a second isolated node; a fourthtermination with a fourth impedance; a second receiver; and secondswitching circuitry that switchably couples the second coupled node andthe second isolated node to the second receiver, the second termination,and the fourth termination.
 5. The electronic device of claim 4, whereinthe first impedance, the second impedance, the third impedance, and thefourth impedance are adjustable.
 6. The electronic device of claim 3,wherein the second signal coupler comprises: a second coupled node; asecond isolated node, the second termination being coupled to the secondisolated node; and a power detector coupled to the second coupled node.7. The electronic device of claim 1, wherein the first signal couplercomprises: a first coupled node; a first isolated node, the firsttermination being coupled to the first isolated node; and a first powerdetector coupled to the first coupled node.
 8. The electronic device ofclaim 7, wherein the second signal coupler comprises: a second couplednode; a second isolated node, the second termination being coupled tothe second isolated node; and a second power detector coupled to thesecond coupled node.
 9. The electronic device of claim 1, wherein thefirst impedance is adjustable.
 10. The electronic device of claim 1,wherein the first signal coupler and the second signal coupler at leastpartially overlap a same segment of the signal path.
 11. The electronicdevice of claim 1, further comprising: a substrate having a firstdielectric layer, a second dielectric layer on the first dielectriclayer, and a third dielectric layer on the second dielectric layer;first conductive traces on the first dielectric layer, the first signalcoupler including the first conductive traces; second conductive traceson the second dielectric layer and at least partially overlapping thefirst conductive traces, the signal path including the second conductivetraces; and third conductive traces on the third dielectric layer and atleast partially overlapping the second conductive traces, the secondsignal coupler including the third conductive traces.
 12. The electronicdevice of claim 11, further comprising: a third signal coupler coupledto the signal path and having a third termination with a third impedancedifferent from the first impedance and the second impedance; and fourthconductive traces on the second dielectric layer, the third signalcoupler including the fourth conductive traces.
 13. The electronicdevice of claim 1, wherein the signal source comprises a poweramplifier, the signal comprises a radio-frequency signal, and the outputload comprises an antenna.
 14. A method of operating an electronicdevice, the method comprising: with a signal source, transmitting asignal along a signal path; with a first signal coupler coupled to thesignal path, measuring a power wave of the signal at a first referenceplane along the signal path; and with a second signal coupler coupled tothe signal path, measuring a power wave of the signal at a secondreference plane along the signal path concurrent with measurement of thepower wave at the first reference plane by the first signal coupler, thesecond reference plane being different from the first reference plane.15. The method of claim 14, wherein measuring the power wave of thesignal at the first reference plane comprises measuring a forward wave(FW) and a reverse wave (RW) of the signal at the first reference plane.16. The method of claim 15, wherein measuring the power wave of thesignal at the second reference plane comprises measuring a FW and a RWof the signal at the second reference plane.
 17. The method of claim 14,further comprising: adjusting a termination impedance of the firstsignal coupler to shift the first reference plane along the signal path.18. The method of claim 17, further comprising: adjusting a terminationimpedance of the second signal coupler to shift the second referenceplane along the signal path.
 19. An electronic device comprising: anantenna; a power amplifier coupled to the antenna over a signal path andconfigured to transmit a radio-frequency signal on the signal path; afirst signal coupler coupled to the signal path; a second signal couplercoupled to the signal path; and one or more processors configured tomeasure the radio-frequency signal at a first reference plane along thesignal path using the first signal coupler, and measure theradio-frequency signal at a second reference plane along the signal pathusing the second signal coupler concurrent with measurement of theradio-frequency signal at the first reference plane using the firstsignal coupler, the second reference plane being different from thefirst reference plane.
 20. The electronic device of claim 19, whereinthe first signal coupler has a first termination with a first impedance,the second signal coupler has a second termination with a secondimpedance different from the first impedance, and the one or moreprocessors is configured to adjust the first impedance of the firsttermination to shift a location of the first reference plane along thesignal path.